Crystal Structure of Mycobacterium tuberculosis Elongation Factor G1

Abstract

Mycobacterium tuberculosis (Mtb) caused an estimated 10 million cases of tuberculosis and 1.2 million deaths in 2019 globally. The increasing emergence of multidrug-resistant and extensively drug-resistant Mtb is becoming a public health threat worldwide and makes the identification of anti-Mtb drug targets urgent. Elongation factor G (EF-G) is involved in tRNA translocation on ribosomes during protein translation. Therefore, EF-G is a major focus of structural analysis and a valuable drug target of antibiotics. However, the crystal structure of Mtb EF-G1 is not yet available, and this has limited the design of inhibitors. Here, we report the crystal structure of Mtb EF-G1 in complex with GDP. The unique crystal form of the Mtb EF-G1-GDP complex provides an excellent platform for fragment-based screening using a crystallographic approach. Our findings provide a structure-based explanation for GDP recognition, and facilitate the identification of EF-G1 inhibitors with potential interest in the context of drug discovery.

The Structural and Molecular Mechanisms of Mycobacterium tuberculosis Translational Elongation Factor Proteins

“…EF-G sequence comparison among different species showed that Mtb EF-G has high sequence similarity (>70%) with Aspergillus fumigatus and Arthrobacter globulus, but shows 55-58% similarity with E. coli and T. thermophilus (Figure 6) [68]. The structures of EF-G protein from T. thermophilus [65], E.coli [70], Mtb [68], Staphylococcus aureus [63], and Bacillus subtilis (PDB:5VH6) have been reported.…”

“…EF-G sequence comparison among different species showed that Mtb EF-G has high sequence similarity (>70%) with Aspergillus fumigatus and Arthrobacter globulus, but shows 55-58% similarity with E. coli and T. thermophilus (Figure 6) [68]. The structures of EF-G protein from T. thermophilus [65], E.coli [70], Mtb [68], Staphylococcus aureus [63], and Bacillus subtilis (PDB:5VH6) have been reported. Among them, the complex structures of EF-Tu with different components including ribosome, GDP, GDP analogs, tRNA, and RRF in T. thermophilus and E. coli were obtained by X-ray crystallography or electron microscopy methods (Table 3).…”

“…Compared to the ribosome in the classical state ribosome [67], the 70S-tmRNA-EF-G complex has undergone large-scale conformational changes [66]. In Mtb, EF-G is a promising target for drug design [68]. Fusidic acid (FA), a drug widely used to treat tuberculosis in the clinic, inhibits Mtb protein synthesis by binding to EF-G and preventing its release after GTP hydrolysis and translocation [68,69].…”

“…In Mtb, EF-G is a promising target for drug design [68]. Fusidic acid (FA), a drug widely used to treat tuberculosis in the clinic, inhibits Mtb protein synthesis by binding to EF-G and preventing its release after GTP hydrolysis and translocation [68,69].…”

“…Domain IV of EF-G acts as a mediator in the translation [10]. The five domains fold into an elongated shape (Figure 7) [68] that is similar to the ternary complex of aa-tRNA-EF-Tu•GTP [10]. This is probably the best known example of molecular mimicry, and emphasizes the need for both the EF-G and the aa-tRNA-EF-Tu•GTP ternary complex to occupy a similar position at the ribosomal subunit interface [10] (Figures 7 and 8).…”